Mat switch having a pair of reinforcing members on the outside surface of the contact plates



Nov. 1, 1966 D. D. HORTON 3,283,096

MAT SWITCH HAVING A PAIR OF REINFORCING MEMBERS ON THE OUTSIDE SURFACE OF THE CONTACT PLATES Filed July 16, 1964 Z flee 17. Hoffa/7 INVENTOR.

ATTORNEY United States Patent 3,283,096 MAT SWITCH HAVING A PAIR OF REINFORCING MEMBERS ON THE OUTSIDE SURFACE OF THE CONTACT PLATES Dee D. Horton, Corpus Christi, Tex., assignor to Horton utomatics, Inc., Corpus Christi, Tex., a corporation of exas Filed July 16, 1964, Ser. No. 383,149 Claims. (Cl. 200-86) This invention relates to new and useful improvements in a switching mat.

It is an object of the invention to provide a switching mat for use in controlling electrical mechanisms such as door operators, having novel means for eliminating fatigue in the contact members of the mat.

It is another object of the invention to provide a switching mat for door operators and the like, having a novel construction of its contact members to strengthen said members and to resist creasing or bending of said members.

In switching mats presently employed in the trade, the metallic contact members are yieldably maintained in opposed relation, usually by nonconductive grommets between the contact members, and sharp objects or excessively heavy objects impacting the mat, results in bending or creasing the contact members and brings about failure of the mat through shorts and resulting self-destruction. It is an object of this invention to provide a switching mat having means for reinforcing the contact members and consequently resisting the tendency to crease or bend under unusually sharp or heavy impacts.

The contact members presently employed in this art are necessarily composed of a heavy .guage metal, as heavy as can be employed and still obtain the necessary yield to make contact between the contact members and still retain the ability to move back into spaced relation. This results in arcing at the point of contact, resulting in pitting of the surface of the contact members from the resulting contact heat, resulting in pitting of the surface of the contact members, bringing about dead areas, which will fail to complete a connection when another contact is attempted at the same place, and thus severely limiting the life of the mat. It is an object of this invention to provide means for employment of much thinner sheets of contact material, which is reinforced, providing a more flexible and actually much stronger \contact member, and which will readily dissipate the heat of arcing over a much greater surface and thus avoiding pitting of the contact surfaces.

With the present type of switching mat, the contact members being necessarily of as heavy .guage as can be employed, the mat is heavy and cumbersome and difficult to ship, handle and install without damage. It is an object of this invention to provide a mat of much less weight than the presently used and less vulnerable to damage through shipping, handling or installation.

With the above and other objects in view, the invention has relation to certain novel features of construction, operation and arrangement of parts, more particularly defined in the following specifications and illustrated in the accompanying drawings, wherein:

FIGURE 1 is a perspective view of the switching mat shown installed in position to control a set of door control operators, and

FIGURE 2 is a cross sectional elevational view taken on the line 22 of FIGURE 1.

Referring now more particularly to the drawings, the numeral 1 designates a housing of rubber, or the like, forming a tread cover having the contact chamber 2 in which are mounted the upper contact plate 3 and the ice lower contact plate 4. The contact plates 3, 4 are of a thin conductive material, of approximately .002" in thickness, and are laminated to a fiberglass reinforced plastic sheet, as 5, 6. Polyesters, or similar type of plastic, may be employed in formulating the fiberglass reinforced sheets 5, 6 and because of the thinness of the conductor material and the low coefficient in expansion of the fiberglass reinforced plastic, the buckling and shorting of the contact members experienced in use of the presently employed type of mat, is eliminated.

A suitable nonconductive marginal separator 7 is mounted between the contact members 3, 4 and additional spacer pads as 8 are mounted at spaced intervals between said contact members in the usual manner.

The switching mat is mounted in the area of use, such as over the approaches of an electrically controlled operator equipped glass door 9, as a load is placed on the mat 1, contact is made between the members 3, 4 and :the switching action effected. The thinness of the conductor material will rapidly disperse the electric contact heat :over a large area, preventing the pitting of the material and causing a dead spot to be formed in the material.

The resistance of the contact members 3, 4 to creasing and bending when reinforced by the fiberglass plastic will permit the use of a much thinner housing than any presently on the market, thus reducing the Weight of the mat, and greatly facilitating the shipping, handling and installation thereof.

While the foregoing is considered a preferred form of the invention, it is by way of illustration only, the broad principle of the invention being defined by the appended claims.

What I claim is:

1. In a switching mat, a housing having a contact plate receiving chamber, upper and lower contact plates having outer and inner surfaces and being mounted in said chamber, yieldable nonconductive separating means between said upper and lower contact plates for normally maintaining the inner surface of said plates out of contact with each other and for permitting contact between said inner surfaces of said plates when a load is placed on said housing, said contact plates having fiberglass reinforced plastic supporting members of equal marginal dimensions bonded to the outer surfaces thereof.

2. In a switching mat, a tread housing, a chamber in said housing, contact members in said chamber having inner and outer surfaces and having spacing means for maintaining said members yieldably spaced apart and permitting contact of said inner surfaces of said contact members upon receiving a load on said tread housing and having fiberglass reinforced plastic supporting members of equal marginal dimensions bonded to the outer surfaces thereof, said supporting members abutting the upper and lower walls of said chamber.

3. In a switch mat, a yieldable tread housing, a chamber in said housing, contact members having inner and outer surfaces, the inner surfaces thereof being normally spaced apart in said chamber, spacing members yieldably maintaining said contact members apart and permitting contact between the inner surfaces of said contact member upon receiving a load on said tread housing, said contact members comprising a thin sheet of conductive material bound on the respective outer surfaces to sheets of fiberglass reinforced plastic, one sheet of said plastic abutting the upper wall of said chamber and the other sheet of said plastic abut-ting the lower wall of said chamber.

4. In an article of manufacture, a switch mat formed of yieldable material and having a tread area, a chamber in said mat of an area substantially the same as the tread area of said mat, sheets of fiberglass reinforced plastic in said chamber, sheets of conducting material in said chamber having outer and inner surfaces, one of said sheets of fiberglass being bonded to the respective outer surface of each of said sheets of conducting material which are mounted longitudinally in said chamber and spacing means normally separating said sheets of conducting material in opposing relation in said chamber for selectively permitting contact between said contacting plates.

5. In a switching mat, a tread housing, a chamber in the said tread housing, opposing contact members in said chamber having outer and inner surfaces, means for preventing buckling or creasing of said con-tact members consisting of sheets of reinforced plastic material 4 said contact member-s and abutting the upper and lower inside walls of said chamber, respectively, the inner surfaces of said contact members being adapted to be moved into contacting relation with each other and to complete an electrical circuit and means for maintaining said members yieldably apart.

References Cited by the Examiner UNITED STATES PATENTS BERNARD A. GILHEAN, Primary Examiner.

generally contiguous with the outer surface of each of 15 LEWITTER, Assistant Examiner- 

5. IN A SWITCHING MAT, A TREAD HOUSING, A CHAMBER IN THE SAID TREAD HOUSING, OPPOSING CONTACT MEMBERS IN SAID CHAMBER HAVING OUTER AND INNER SURFACES, MEANS FOR PREVENTING BUCKLING OR CREASING OF SAID CONTACT MEMBERS CONSISTING OF SHEETS OF REINFORCED PLASTIC MATERIAL GENERALLY CONTIGUOUS WITH THE OUTER SURFACE OF EACH OF SAID CONTACT MEMBERS AND ABUTTING THE UPPER AND LOWER INSIDE WALLS OF SAID CHAMBER, RESPECTIVELY, THE INNER SURFACES OF SAID CONTACT MEMBERS BEING ADAPTED TO BE MOVED INTO CONTACTING RELATION WITH EACH OTHER AND TO COMPLETE AN ELECTRICAL CIRCUIT AND MEANS FOR MAINTAINING SAID MEMBERS YIELDABLY APART. 